Summary: IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 40, NO. 1, JANUARY 2004 41
Quantum Noise of Actively Mode-Locked Lasers
With Dispersion and Amplitude/Phase Modulation
Farhan Rana, Rajeev J. Ram, and Hermann A. Haus
Abstract--A quantum theory for the noise of optical pulses in
actively mode-locked lasers is presented. In the presence of phase
modulation and/or group velocity dispersion, the linear operator
that governs the time evolution of the pulse fluctuations inside
the laser cavity is not Hermitian (or normal) and the eigenmodes
of this operator are not orthogonal. As a result, the eigenmodes
have excess noise and the noise in different eigenmodes is highly
correlated. We construct quantum operators for the pulse
photon number, phase, timing, and frequency fluctuations. The
nonorthogonality of the eigenmodes results in excess noise in the
pulse photon number, phase, timing, and frequency. The excess
noise depends on the frequency chirp of the pulse and is present
only at low frequencies in the spectral densities of the pulse noise
operators.
Index Terms--Laser noise, optical pulses, quantum optics, ultra-
fast optics.